1. Field of the Invention
This invention relates to conduits used to transport cryogenic fluids.
2. Description of the Prior Art
U.S. Pat. No. 3,904,394 discloses a fluid transfer line having transport tubes suspended within a polymeric radiation shield by nylon wires. Cooling tubes outside the radiation shield, one cooling tube thermally connected to the shield by a heat conductive paste inside a copper foil envelope and a second cooling tube outside the copper foil envelope urging the copper foil envelope against the exterior of the first cooling tube, maintain the radiation shield at a low temperature via fluid transport through the cooling tubes. The entire assembly is enveloped by a gauze-mylar blanket and suspended within a stainless steel tube at selected intervals.
U.S. Pat. Nos. 3,986,341; 3,992,169 and 4,036,618 share a common disclosure which shows both rigid and flexible sections of a cryogenic transport line. A refrigerant line is provided outside of aluminum foil which surrounds a transport conduit. The refrigerant line is not rigidly connected to either the aluminum foil and mylar positioned between the refrigerant line and the transport conduit or to the inner transport conduit; this results in a sliding shield assembly about the inner transport conduit. The aluminum foil and mylar in concentric layers yield the sliding shield insulating the transport conduit. The entire assembly is encased with a carbon steel jacket. Expansion joints utilize stainless steel bellows within the inner transport conduit. The inner transport line and the intermediately spaced refrigerant lines are supported by two concentric aluminum rings connected by fiberglass spokes, with the fiberglass projections extending off the aluminum rings to support the refrigerant lines. The outer ring is spaced away from the interior of the outer housing by fiberglass spokes to provide only point contact between the ring and the housing.
U.S. Pat. No. 1,891,740 discloses a method for producing an extruded one-piece object having an open perimeter which becomes a closed perimeter when two complemental mating portions are snapped together.
U.S. Pat. No. 3,459,234 discloses a tubular assembly formed of two interlocking members which, when assembled, have a raceway extending longitudinally therealong, interior of the tube. The raceway is open to allow sail keepers to move slidably therealong. Teeth on the interlocking members effectively prevent disengagement.
U.S. Pat. No. 3,055,399 discloses an elongated hollow conduit formed of two pieces having overlaping margins, with the margins provided with and aligned by longitudinally extending grooves and thereafter being bonded together with epoxy to define the conduit.
The prior art fails to disclose a cryogenic fluid transfer line which can be easily and quickly assembled without substantial amounts of welding and necessarily associated high labor costs.